The invention relates to a rotary piston internal combustion engine having a casing comprised of two side portions and a center portion with a trochoidal inner mantle surface, the casing being penetrated by an eccentric shaft having an eccentric on which a triangular, oil-cooled piston rotates on a friction bearing whereby its edge sealing members are in constant contact with the inner mantle surface.
Such machines are commonly provided with an oil sump that is upwardly open and into which the lubricating and cooling oil drains and from where the oil is returned through oil filter and oil cooler into the bearings and the piston. Such an arrangement allows for a lateral tilting of the machine, which must be taken into consideration when driving an off-road vehicle or plane, only for a limited angular range because otherwise the oil supply from the oil sump is interrupted and air is sucked into the oil circuit or oil drains from the oil sump. A closed oil circuit has not been suggested for rotary piston internal combustion engines as of today and it can be realized for lifting piston machines, for example, for planes for air aerobatics, only with great constructive expenditure.
It is an object of the invention to construct a rotary piston internal combustion engine without oil sump which is position-independent, i.e., which can be tilted by 30.degree. and more about its horizontal longitudinal and transverse axes and even into an upside-down position, which can be stored in such positions for an extended period of time, and which is compact and has a minimal end face resistance.